When players walk away or are forcibly removed from the game, the circumstances under which they leave determine how their careers will be remembered.

Was it time for them to hang it up? Did re-occurring injuries force the issue? Was self-inflicted spite at the heart of their farewell?

Bidding goodbye to players, specifically stars, who people admired or were supposed to be something special is never easy. But when a player leaves on his own terms, on the right terms, it can be an uplifting occasion. They came, they played, they conquered—there is solace to be found in knowing that.

Not all stars find that closure. Or provide us with closure of our own.

Many players have taken off, be it because of injuries or bruised egos, leaving a trail of unanswered and unsettling "what ifs" in their wake.

Spree rejected a three-year $21 million contract offered to him by the Minnesota Timberwolves because he had a family to feed. That didn't pan out for him so well.

After averaging a career-low 12.8 points per game in 2004-05, Spree never played in the NBA again. Whether you liked him or not, his demise was off-putting. He still had the potential to be a valuable scorer on a contending team.

But he allowed his own hubris and ignorance to get in the way of his career, one that stood to be derailed after he physically assaulted then head coach P.J. Carlesimo in 1997.

While he navigated the labyrinth of controversy then, his worst enemy—himself—inevitably caught up with him.

Honorable Mention: Brandon Roy

Degenerative knees forced Brandon Roy to retire once, and after a comeback attempt with the Minnesota Timberwolves this past season, it seems unlikely the sharp shooter will ever play in the NBA again.

Nothing too definitive has surfaced, hence the honorable mention, but even if Roy were to give it another go, it would never be like it was.

In five years with the Portland Trail Blazers, he made three All-Star teams, bursting onto the scene as one of the league's premier shooters. He averaged at least 16 points per game in each of his first four seasons before injuries sparked a drastic decline in 2010-11.

After sitting out the entire 2011-12 season, the hope was that he could experience a renaissance of sorts in Minnesota. Bedeviled by injuries yet again, Roy appeared in just five contests.

One year after trying to overcome what was deemed a career-ending injury, no resurgence of any kind appears to be in the cards.

Drazen Petrovic

I waffled back and forth on Drazen Petrovic's inclusion. Was he really a star? Last-minute style, I came to the answer of "yes." A rising star, but a star nonetheless.

Drafted by the Portland Trail Blazers in 1986, Petrovic wen on to broach stardom with the New Jersey Nets. Upon arrival, his scoring averages jumped as he notched 20-plus points per game in the two full seasons he spent with the team.

Tragedy struck in the summer of 1993, though. Petrovic was killed in a car crash in Germany at the age of 28.

No one knows what would have happened once the 1993-94 season began. His volume scoring could have made for a long and prolific NBA career, or those two years of offensive dominance in New Jersey could been rendered an aberration. Once again, we just don't know.

Maurice Stokes

Maurice Stokes is one of the best NBA players some people have never heard of.

ESPN.com's Curtis Harris described Stokes—who played during the 1950's—as a "burly, fast and exciting power forward," and it's not difficult to understand why.

In each of his first three seasons, Stokes was named to the All-Star team. His shooting percentages weren't great, but he was able to score and hoard rebounds in excess.

Stokes' career was cut way short, however, after he fell on his head against the Minneapolis Lakers in 1958. Knocked out at first, Stokes eventually regained consciousness and returned to the game, according to Harris.

Just a few days later, he suffered multiple seizures that left him permanently paralyzed, ending his career before it even had enough time to really start.

Over the course of his career, Johnson earned 12 All-Star selections (11 appearances), five championships, three league MVPs and three finals MVPs. Today, he is recognized as one of the best players ever, someone who LeBron James is constantly compared to.

That kind of great.

Twelve seasons into his tenure with the Los Angeles Lakers, however, he tested positive for HIV. Though he returned to play 32 games for Los Angeles in 1995-96, his illness effectively ended his career at the age of 32. The 36-year-old Magic that took the floor in his "last" season, wasn't the same player he was four years prior.

Declines are to be expected as players age, but Magic's career "ended" so abruptly no closure could be found.

Who's to say he couldn't have led the Lakers to another championship? Or two? Or three? Who's to say that one of the NBA's greatest couldn't have been even better?

The do-it-all guard carved out a 14-year career, but knee injuries abounded beginning in 1997. Multiple surgeries ensured Hardaway would only appear in 75 or more games twice during the final 10 seasons of his career.

What happened to him was truly a shame. He went from being a four-time All-Star to a serviceable reserve who couldn't stay healthy in a span of just a couple seasons.

Had his knees never failed him, he was on pace to garner just as many Magic comparisons then as LeBron is now. Greatness was among us.

Then suddenly, it wasn't.

The last decade or so of his career wasn't indicative of the player he was supposed to be. He averaged just over 50 games a season for his career, and after a failed comeback attempt with the Miami Heat during the 2007-08 campaign, he called it quits.

Ralph Sampson

Before Tim Duncan joined David Robinson to form the Twin Towers, the Houston Rockets had a pair of skyscrapers all their own in Ralph Sampson and Hakeem Olajuwon. Then just like that, they didn't.

Standing at 7'4", Sampson was quite the physical specimen, averaging at least 21 points and 10 rebounds through the first two seasons of his career. He and The Dream led Houston to the 1986 NBA Finals, where the Rockets came two victories away from a championship.

Sadly, there wound up being nowhere to go but down for Sampson after that. His production gradually decreased, courtesy of the losing battles he waged against his knees and back, and he never appeared in more than 61 games again.

This was a guy that went from brutalizing the competition by notching gaudy double-doubles, to averaging no more than 6.4 points a night throughout his final four years.

By the end of the 1991-92 season, during which he played just 10 games, he was finished, leaving us to wonder what could have been.

Points were scored, All-Star selections had (11) and league MVPs won (one). There was also practice, but Iverson didn't care too much for that.

Though he benefitted from the near absence of advanced analytics, Iverson was one of the greatest scorers there ever was. But his career was cut short by his ego.

Imagine if he had been willing to come off the bench or even spend some time in the D-League. There were opportunities for him to continue playing. He just failed to seize them.

Had he accepted not even a diminished, but different role, he could have been a star sixth man in the league well beyond 34, the age at which he played in his last NBA game. Instead, the now 38-year-old Iverson is set to announce he's officially retiring, according to Slam's Tzvi Twersky.

Yao Ming

Once upon a time, Yao Ming's popularity didn't dwarf his health. He appeared in at least 80 games in each of his first three seasons, emerging as a dominant post presence on the offensive end and glass in general. Might I remind you that most of those eight All-Star selections (six appearances) were earned, not merely a product of his global appeal.

Plagued by lower-body injuries the latter half of his career, Yao spent his final five seasons struggling to make any appearances at all. Save for the 2008-09 crusade, during which he played in 77 games, Yao never took the floor for more than 57 contests in a single season.

When he was healthy, he could score with the best; he averaged at least 22 points a night in three consecutive seasons between 2005-08. Problem was, he was almost never healthy.

One year after sitting out the entire 2009-10 campaign, Yao's swan song consisted of five appearances to start the 20010-11 season. Unable to continue playing, he retired in the summer of 2011, prematurely ending a career that should have spanned much longer than eight seasons.